The present invention relates generally to remotely monitored security systems that have audio information gathering capability and, more particularly, to a device and method for enhancing the effectiveness of security systems that record audio information at the monitored premises.
A security system located on the site of a structure to be monitored typically consists of a local control unit connected to one or more detectors placed at strategic points in the structure. The detectors may include contact switches, pressure switches, infrared sensors, ultrasonic sensors, smoke or fire detectors, or any of the types that are commonly used in security systems. In addition, some security systems, known as emergency response systems, have a manually operated transmitter that an elderly or infirm person can use to activate the security system.
Upon the occurrence of an event such as the opening of a door or window or the activation of an emergency response transmitter, the security system alerts personnel at a monitoring center located at a remote site. The personnel at the monitoring center can then respond to the situation. Such action typically includes dispatching security personnel or police to the premises.
False alarms are a serious problem in security systems. Not only does dispatching security personnel or police in response to a false alarm waste resources, but in many communities it subjects property owners to fines if police are repeatedly summoned. To avoid such problems, security systems may transmit additional information following the initial notification to aid monitoring personnel in distinguishing false alarms from alarms occurring in response to actual events that the security system is intended to detect. For example, a security system may transmit information identifying the premises and the type and location of the particular detector that triggered the alarm.
The additional information transmitted to monitoring personnel may also include sounds occurring at the premises immediately preceding or following the initial notification. A security system may have one or more microphones placed at strategic locations in the structure. Via the telephone connection or radio link established by the activation of the alarm, monitoring personnel can listen to sounds on the premises or, in some systems, speak to those on the premises. The latter allows the verification of the alarm situation through a verbal challenge to the occupants of the structure. Should the alarm activation be confirmed as harmless, the response protocol could be terminated at a relatively early stage without the unnecessary expenditure of scarce resources. The use of such a system also allows remote personnel to deduce the exact nature of a manually-activated alarm and tailor their actions accordingly.
Security systems that allow monitoring personnel to hear sounds occurring at the premises have been improved by including audio recording or storage devices at the monitored premises for storing any sounds that may have occurred prior to or following the activation of the alarm. Such "stored-audio" systems commonly have a continuous-loop audio tape as a storage medium located on the monitored premises. The security system continuously records ambient sound until the alarm is activated. Via the telephone connection or radio link established by the activation of the alarm, monitoring personnel can play back the recorded sounds. Stored-audio systems may allow monitoring personnel to remotely select either the stored audio or the "live" audio captured in real-time by the microphones.
Responding to the activation of a stored-audio security system presents monitoring personnel with a dilemma. If they select the stored audio they may miss critical sounds occurring at the premises, such as a cry for help, while they are listening to the stored audio. If they select the live audio they may miss sounds that occurred prior to the activation of the alarm, such as the sound of shattering glass. It would be desirable to provide monitoring personnel with an indication of whether any sound information has been recorded that has a quality or length sufficient to aid personnel in identifying the source of the sounds. These problems and deficiencies are clearly felt in the art and are solved by the present invention in the manner described below.